Giovanni pictured in 1986 flanked by bodyguards. Six years later he was dead, assassinated by the Sicilian mafia. (Getty)

Four members of the Sicilian mafia have been sentenced for murdering anti-mob judge Giovanni Falcone in 1992.

Giuseppe Barranca and Cristoforo Cannella were sentenced to life in prison for their role in the killing, in which the anti-mafia prosecutor's car was blown up using more than half a ton (500 kg) of explosives.

Cosimo D'Amato was handed 30 years in jail, while Gaspare Spatuzza received a reduced 12-year sentence after helping police secure the convictions of the three other former mobsters.

Falcone's wife and three police officers were also killed in the attack, on a motorway near Palermo, Sicily.

Convicted murderer Spatuzza told a Milan court earlier this year that he had been responsible for scores of deaths during his time as a mobster.

"I am responsible for about 40 murders. I ask forgiveness from the city, from the victims and from their relatives," he said.

He is currently serving a life sentence for his role in six bomb attacks in 1992 and 1993, but may serve a reduced sentence under an Italian law which allows criminals who no longer pose a danger to society to be released early.

As well as leading anti-mafia magistrates, cultural landmarks such as the Uffizi Gallery in Florence and Milan's Galleria d'Arte Moderna were also targeted in the campaign.

Spatuzza's evidence was crucial in the convictions of the three, revealing how the explosives were obtained for the deadly attack on Falcone.

The slaying of Falcone and another judge involved in anti-mafia investigations, Paolo Borsellino, the following year caused international outrage, and allegedly led the Italian government to enter in to secret talks with Cosa Nostra in a bid to end the campaign of violence.

Both slayings were ordered by mafia chief Toto Riina, who was arrested in 1993 and is now serving multiple life sentences in a maximum security jail.